Method of making hollow bodies



Jan. 1a, 1938.

1.. c. SHIPPY ET AL 05,704

Filed Aug. 25, 1933 5 g INVENTOR 15.0 jfi/FP VV/LMAR [750m 555m BY lglmw Y- 754 ATTORNEYS Patented Jan. 18, 1938 METHOD: .OF' MAKING HoLIiow BODIES 'Leo;C. Shippy, Lockport, N. Y,, and 'Wilmar Oscar Gebhart, -Anderson,.;lnd., vassignors, by mesne assignments; to. General Motors Corporation, v Detroit, Mich; a corporation of Delaware Application August 25, 1933', Serial No. 686,756

. lfi e ms-a 1- 3-5 This invention relates to the moldingko'f holshoulder being flush with the bottom 28 of the low bodies, and more particularly to' hollow bodies recess 22 of the die member 2|]. A pill or "presuch as knobs or handles used on-theend- 'ofa form 29 'of uncured Bakelite and having an gear-shift lever of automotive 'i'rehiclesi' aperture 30 is placed'cverthe. end 25 and rests An object of the. present invention is mph)- upon the metal insert 26. A ring 3! and a second vide a hollow body which will be strcng-and*du'- disc 32 having an aperture 33 of uncured Bakerable and will require but a minimumarnount o1 lite is placed above the disc 29 insuch a man- Bakelite or artificial'res'in'ous compoundini-ts ner that an air chamber34 is formed. The upproduction. I per die member 2| is then placed over the mold Another object of the present invention is 'to material. The die members 20 and 2! are then 10 prevent the accumulation of cured "Bakeli'te 'or operated'at a temperature-and pressure such as other artificial resinous compound at'the i'nner ordinarily used in molding operations. The die end of a threaded insert'which is molded in the members are closed rapidly, the reduced end 25 hollow knob to provide means for attaching the of the pin 24 closing the aperture 33 0f the disc knob to an end of alever. By preventing the ac- 32 so that the air within the chamber 34 is 15 cumulation of a substantial amount of Bakelite" trapped. By'reason of the. air being trapped withat the inner end of the threaded insert the wear in thechamber 34 the finished mol-dedarticle will and tear on taps used to clean out- 'Bakeli te be hollow,'as the trapped air within the chamber from the insert is materially-reduced. This is 34. prevents the plastic material from flowing toaccomplished by first placing a threaded'insert ward the center of the chamber, thus preventing into a mold, and then "arranging uncured pills the accumulation of the plastic. material from or preforms of Bakelite or artificial resin entering into the threaded portion of the insert above the insert in such a mannerthat a center 6, but allowing the.Bakelite while in a plastic void or air chamber is formed above' the insert. form to surround the knurled section of the in- All of the preio-rms are then subjected to a'mold sert and along the walls of the die members to 2.; ing operation that Will trap air in the air chamber form a shell of substantial uniform thickness so as to keep the plastic materialirom flowing throughout. toward the center of the chambjer'andawa'y from After the pr and at v n app ied the threaded portion of the insert." for a sufficient length of time, the die members 3 Further objects and advantages of the present are separated. On separation of the die mem- 3c invention will be apparent fromthe following-(le beats the compressed air within the chamber will scription, reference being hadtq-the-accompanycause the'knob or'm'olded body to loosen itself jng drawing, r i a preferred emb di t of from the die member 26 so that the knob may-be one form of the present invention is clearly easily eremov'edr The oc ut mechanism shown. usually employed for removing the work has not 3.

In the drawing: been shown, it being understood that such mech- Fig. 1 is a longitudinal sectional view showing anism s Well now and W ll be used when rethe initial stage of a molding press in a sepaq rated position and associated posts required to It is obvious that the present invention mate- 40 manufacture one of the improved knobs. rially reduces the cost of manufacture of hollow 10 Fig. 2 is a view similar to Fig. 1 showing he knobs of molded material. Not only is less moldld n D s in a closed positioning material required, but the wear and tear of Referring to the drawing a lower die member the taps that are used to clean out the Bakelite and an upper die 'f are provided with from the threaded portion of the inserts is mate- 4:) recesses 22 and 23 respectively. The recess 22 is riauy reduced coaxial with respect to a knock-out pin 2G slidably The term Bakelite is understood to include supported by the die member 2!). The pin 24 generally molding compounds which are cured is provided with a reduced end 25, upon which is der the application of pressure or heat and placed a short knurled sleeve or insert 26, havpressure ing through internal threads, which is molded 50 into the kn b the operatior While the form-Of embodiment Of the present Describing the pr f rred method employed in invention as herein disclosed, constitutes a precarrying out this invention, the insert 26 is placed ferred f l it is be understqod t at othe over the reduced end 25 so that one end thereof fOrmS ght be adopted, all Commg Withm t will rest on the shoulder 2'! of the pin 24, said scop of the claims which ol ow. 55

What is claimed is as followst 1.The method of making hollow bodies, comprises the steps which include, arranging two disc preforms and one ring preform of uncured phenolic condensation material in a mold in a manner such as to form a central void, closing the mold quickly to trap the air in the void and then subjecting the preforms to heat and pressure within the mold to cause the material to flow along the walls of the mold and to keep the material away from the center of the body, and releasing the air from the body whereby the body is loosened from the mold.

2. The method of making hollow bodies, comprises the steps which include, arranging superimposed preforms of uncured moldable material upon each other in a manner such as to provide an air pocket, one of the preforms has an aperture to permit air between the preform and mold to be forced within the preforms, applying suflicient pressure to bring the mold together to trap in air between the preforms, heating the material while the air is trapped to keep the flow of material away from the center of the body, and then allowing the air to escape to loosen the body from the mold. 3. The method of making a hollow member, comprises the steps which include, placing a disc of uncured molding material around a central locating pin in the lower half of the mold, placing a ring of uncured molding material over the disc, placing a disc of uncured molding material over the ring and forming a central void, closing the upper half of the mold quickly to trap air in the void and then subjecting the preforms to heat and pressure to cause the molding material to flow along the walls of themold members while the trapped air tends to keep the molding material from the center of the member, and then allowing the air to escape to free the body from the molds.

4. The method of making hollow knobs having a metallic sleeve, comprises the steps which include, placing a metal sleeve in the lower half of the mold, placing preforms of uncured molding material in the mold in a manner such as to form a central void, closing the upper mold quickly to urge the sleeve against the lower mold to trap the air in the void and subjecting the preforms to heat and pressure within the molds to cause the molding material to flow along the walls formed by the molds while the trapped air tends to keep the flow of molding material away from the interior of the sleeve, and then releasing the trapped air through the sleeve.

5. The method of making a hollow knob having a tubular insert comprises the steps which include, placing the insert in the lower half of the mold, placing a preform of uncured new molding compound above the insert, placing a second preform over the first preform, placing a third preform over the second preform forming a central void, closing the upper half of the mold quickly to urge the insert against the lower mold to trap the air in the void and then subjecting these articles within the mold cavities to heat and pressure to expand the air and cause the molding compound to flow along the walls of the cavities and contact with the outer circumference of the insert while the trapped air tends to keep the flow of Bakelite from entering the interior of the insert, and then releasing the trapped air to free the knob from the mold.

6. The method of making knobs provided with a void communicating with the exterior thereof comprising the steps which include, supporting a tubular member in a lower mold, placing preformed members of uncured molding material in a manner to provide a void above the tubular member, closing an upper mold quickly to force the tubular member against the lower mold to prevent escape of air through the sleeve and trap the air between the preformed members, subjecting the preforms to heat and pressure to expand the trapped air in the void and cause the preforms to become plastic and weld together to provide a continuous shell with the air compressed within the same, and then separating the molds allowing the air to escape through the sleeve'and free the knob from the mold.

7. The method of making hollow bodies, comprising the steps which include, arranging superimposed preforms of uncured moldable material upon each other in a mold in a manner such as to provide an air pocket, one of the preforms having an opening allowing air to be forced between the preformsl, applying sufiicient pressure to bring the mold together and closing the opening before the molds are brought together to trap the air between the preforms, subjecting the preforms to heat and pressure to expand the trapped air within the pocket to keep the material away from the center of the body, and then separating the molds allowing the trapped air to escape and free the body from the mold.

LEO C. SHIPPY.

WILMAR OSCAR GEBHART. 

